Graduation Semester and Year

2015

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Aerospace Engineering

Department

Mechanical and Aerospace Engineering

First Advisor

Ashfaq Adnan

Abstract

Ceramic materials are one of the most promising materials for wide variety of technical applications such as automotive, aerospace, medical, and other applications. They have very high strengths and high melting points relative to metals. However, low fracture toughness is one of the main barriers of ceramics prohibiting their wide-spread applications. This is because ceramics are mainly bonded with directional bonds which don’t allow dislocations based deformation. Several attempts have been made to increase the toughness of ceramic materials without sacrificing significantly the other mechanical properties. Here three different types of SiC based ceramics have been computationally (atomistic and up-scaled modeling) developed and studied to understand the deformation mechanism. They are: (1) Nanodiamond reinforced SiC nanocomposites, (2) “carbon” enriched SiC nanostructures and (3) Diamond-SiC nanoscale multilayered films where fraction of “Si” atoms is replaced by “C” atoms. Initial results from atomistic level and subsequent continuum level studies show enhancement in both strength and toughness. Conventional strong but brittle ceramics can't be applied in many future engineering applications where the high stiffness of ceramics is very favorable but unavoidable low toughness is the disappointing point. The outcome of research is shows a successful indication of proposing computationally made a new class of ceramic materials with high hardness as well as desirable high toughness. It will increase the area of applications of ceramic materials and will meet the future demand of desired material properties.

Disciplines

Aerospace Engineering | Engineering | Mechanical Engineering

Comments

Degree granted by The University of Texas at Arlington

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